A Case Report & Literature Review Transient Osteoporosis of the Hip in Association With Osteogenesis Imperfecta: Two Cases, One Complicated by a Femoral Neck Fracture Samuel D. Young III, MD, Charles L. Nelson, MD, and Marvin E. Steinberg, MD ransient osteoporosis of the hip, a relatively internal fixation at age 42. The patient had immediate fam- uncommon cause of disabling hip pain, occurs ily members who also had been diagnosed with osteogen- spontaneously in men during the fourth and fifth esis imperfecta. decades of life and in childbearing females dur- On examination, the patient had a moderate limp favor- Ting the third trimester of pregnancy. It has been described ing the left lower extremity, his sclerae had a blue tinge, in conjunction with osteogenesis imperfecta in 18 cases he had shortened small finger metacarpal bones bilaterally, to date. Meta-analysis has suggested that people with and range of motion (ROM) of the left hip was moderately osteogenesis imperfecta (vs the general population) are restricted and painful at extremes of motion. at increased risk for developing transient osteoporosis, suggesting the role of microfractures in the etiology of transient osteoporosis. “[In men this] occurs In this report, we present 2 additional cases of transient osteoporosis of the hip in conjunction with osteogenesis spontaneously...during the imperfecta, including the first case of a spontaneous patho- fourth and fifth decades logic fracture in a male patient with both disorders. of life” CASE REPORTS Case 1 The patient was initially evaluated at an outside insti- A man in his late 40s with osteogenesis imperfecta pre- tution, where plain x-rays showed osteopenia of the sented with a 5-week history of severe left hip pain. He left femoral head and neck (Figure 1). No fractures or reported spontaneous onset of left hip pain, which over 5 dislocations were noted. A magnetic resonance imaging weeks progressed to incapacitation. There were no precipi- (MRI) scan of the left hip showed a mild effusion of the tating traumatic incidents or other identifiable predisposing hip joint, decreased signal intensity in the left femoral factors. Past medical history was significant for a tarda form head and neck on T1-weighted images, and significantly of osteogenesis imperfecta compounded by multiple previ- increased signal intensity of the femoral head and neck ous fractures. Of significance, the patient had sustained a on T2-weighted images (Figures 2A, 2B). The patient was left femoral neck fracture at age 15, a right femoral shaft then referred to our institution for definitive management. fracture treated with intramedullary fixation in his late 30s, The patient was diagnosed with transient osteoporosis and a left patella fracture treated with open reduction and of the left hip. A regimen of protected weight-bearing with use of 2 crutches was recommended, and he was placed on mild analgesic medications. A week later (or 6 weeks Dr. Young is Assistant Professor, Department of Orthopedic Surgery, University of Florida School of Medicine, Jacksonville, in the course of the disorder), he slipped and sustained a Florida. He was Chief Resident, Department of Orthopedic “torquing” force to the left hip. At that time, he also noted Surgery, University of Pennsylvania School of Medicine, a “snapping” sensation and intense pain in the left hip. He Philadelphia, Pennsylvania, at the time the article was written. proceeded immediately to the emergency department at our institution, where plain x-rays of the left hip revealed Dr. Nelson is Associate Professor, and Dr. Steinberg is Professor Emeritus, Department of Orthopedic Surgery, University of a minimally displaced transcervical femur fracture (Figure Pennsylvania School of Medicine, Philadelphia, Pennsylvania. 3). He underwent percutaneous fixation with three 7.3-mm cannulated screws and was kept on a minimal weight- Address correspondence to: Samuel D. Young, III, MD, 4555 bearing postoperative regimen. Emerson Street, Suite 100, Jacksonville, FL 32207 (tel, 904-633- Two weeks after the operative procedure, the patient 0159; fax, 904-633-0795; e-mail, Samuel. [email protected]). was still suffering from intense pain both during activity Am J Orthop. 2008;37(2):88-91. Copyright Quadrant HealthCom and at rest. Plain x-rays of the left hip revealed satisfactory Inc. 2008. All rights reserved. alignment of the fracture fragments; however, the femoral 88 The American Journal of Orthopedics® S. D. Young et al Figure 1. Case 1—Anteroposterior x-ray of left hip reveals Figure 3. Case 1—Anteroposterior x-ray of left hip shows trans- osteopenia of femoral head and neck. cervical femoral neck fracture. head and neck were notably more osteopenic than in prior The patient, now 5 years after the operative procedure, studies. The patient subsequently underwent a metabolic stated that he had no discomfort in the right hip. He was bone workup that was significant for an increased level of capable of ambulating without assistive devices for an urinary deoxypyridinolene cross-links and a DEXA (dual- unlimited distance without pain. There was no perceivable energy x-ray absorptiometry) scan that revealed a bone limp or leg-length discrepancy. ROM was 120° flexion, 5° mineral density that was less than 3 SD below normal for extension, 40° abduction, 20° adduction, 15° internal rota- his weight and age. He was placed on a course of intrave- tion, and 40° external rotation. Harris Hip Score was 100 nous pamidronate therapy. points (100 possible). Three months after the operative procedure, the pain in the left hip had subsided substantially, and motion had Case 2 improved to a normal range. However, plain x-rays contin- A man in his mid-60s with a history of osteogenesis ued to show evidence of inadequate consolidation of the imperfecta was referred to our institution with a 4-month fracture fragments despite adequate alignment. Weight- history of severe left hip pain. The sudden-onset pain was bearing status was gradually increased, and the patient not associated with antecedent trauma. Within the first underwent a course of electromagnetic bone stimulation. week of onset, the pain was severe enough that the patient Two months later, plain x-rays showed some evidence began to limit weight-bearing. He had been diagnosed with of fracture consolidation, and he was advanced to 50% osteogenesis imperfecta at approximately 3 years of age. weight-bearing. Eight months after the operative proce- He noted that he had sustained as many as 34 fractures of dure, he was fully weight-bearing without pain or use of multiple bones by age 13. All of his children had had mul- assistive devices. Plain x-rays revealed full consolidation tiple fractures, had blue sclerae, and had been diagnosed of the fracture (Figure 4). with osteogenesis imperfecta. A B Figure 2. Case 1—(A) T1-weighted magnetic resonance image of hip shows decreased signal intensity in femoral head and neck suggesting edema. (B) T2-weighted magnetic resonance image of hip shows increased signal intensity in femoral head and neck suggesting edema. February 2008 89 Transient Osteoporosis of the Hip in Association With Osteogenesis Imperfecta Figure 4. Case 1—Anteroposterior x-ray of left hip at 8 months Figure 5. Case 2—Anteroposterior x-ray of left hip reveals follow-up shows healing of femoral neck fracture. osteopenia of femoral head and neck. On examination, the patient had blue sclera, ambulated noted spontaneous resolution of the hip pain. Plain x-rays of with an antalgic gait favoring the left lower extremity, had the hip revealed resolution of the osteopenia of the femoral 20° external and 10° internal left-hip rotation limitations head and neck. (vs the contralateral, unaffected side), and had significant Three years after resolution of the transient osteoporosis, discomfort at the left-hip rotation extremes. the patient reported that the left hip was asymptomatic, except Plain x-rays of the left hip were notable for osteopenia for occasional fleeting discomfort after prolonged immobiliza- involving the left femoral head and neck (Figure 5). MRI tion. He ambulated with a slight limp secondary to a left knee showed decreased signal intensity on T1-weighted images flexion contracture that developed after treatment for a distal and increased signal intensity on T2-weighted images of the femur fracture. Examination of the hip revealed 120° flexion, left femoral head and neck, as well as a small effusion of 5° extension, 15° internal rotation, and 40° external rotation. the hip joint (Figures 6A, 6B). Bone scintigraphy demon- Harris Hip Score was 87 points (100 possible). strated increased uptake in the left femoral head and neck. A diagnosis of transient osteoporosis of the left hip was DISCUSSION made, and the patient was treated nonoperatively with Transient osteoporosis of the hip is an uncommon cause of protected weight-bearing using crutches and analgesics. disabling hip pain. Since it was first described by Curtiss The patient continued to have severe pain despite these and Kinkaid1 in 1959, approximately 500 cases have been measures. Five months after disorder onset, he underwent documented in the literature.2 The disorder afflicts males core decompression to facilitate resolution of this severe nearly 3 times more commonly than females.3 The typical pain. A specimen sent for pathologic examination showed male patient is in his 30s or 40s and has no apparent predis- hypervascular marrow; undecalcified sectioning was not posing conditions. The disorder in females occurs almost performed. Four to 6 weeks after decompression, the patient exclusively in pregnancy during the third trimester.4 A B Figure 6. Case 2—(A) T1-weighted magnetic resonance image of hip shows decreased signal intensity in femoral head and neck suggesting edema. (B) T2-weighted magnetic resonance image of hip shows increased signal intensity in femoral head and neck suggesting edema. 90 The American Journal of Orthopedics® S.